/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.commons.udf.builtin;

import org.apache.iotdb.commons.udf.utils.UDFDataTypeTransformer;
import org.apache.iotdb.udf.api.access.Row;
import org.apache.iotdb.udf.api.collector.PointCollector;
import org.apache.iotdb.udf.api.exception.UDFInputSeriesDataTypeNotValidException;
import org.apache.iotdb.udf.api.type.Type;

import java.io.IOException;

public class UDTFCommonDerivative extends UDTFDerivative {

    @Override
    protected void doTransform(Row row, PointCollector collector)
            throws UDFInputSeriesDataTypeNotValidException, IOException {
        long currentTime = row.getTime();
        double timeDelta = (double) currentTime - previousTime;
        switch (dataType) {
            case INT32:
                int currentInt = row.getInt(0);
                collector.putDouble(currentTime, (currentInt - previousInt) / timeDelta);
                previousInt = currentInt;
                break;
            case INT64:
                long currentLong = row.getLong(0);
                collector.putDouble(currentTime, (currentLong - previousLong) / timeDelta);
                previousLong = currentLong;
                break;
            case FLOAT:
                float currentFloat = row.getFloat(0);
                collector.putDouble(currentTime, (currentFloat - previousFloat) / timeDelta);
                previousFloat = currentFloat;
                break;
            case DOUBLE:
                double currentDouble = row.getDouble(0);
                collector.putDouble(currentTime, (currentDouble - previousDouble) / timeDelta);
                previousDouble = currentDouble;
                break;
            default:
                // This will not happen.
                throw new UDFInputSeriesDataTypeNotValidException(
                        0,
                        UDFDataTypeTransformer.transformToUDFDataType(dataType),
                        Type.INT32,
                        Type.INT64,
                        Type.FLOAT,
                        Type.DOUBLE);
        }
        previousTime = currentTime;
    }
}
